Communication from an aircraft to a satellite or between satellites requires circularly polarized antennas, i.e. antennas which transit circularly polarized radiation, and which have a very wide covering area. If the antenna must be mounted on the surface of the aircraft or the satellite, due to aerodynamic requirements, only limited coverage can be achieved by circular polarization, as described, e.g., by R. J. Mailloux "Phased array aircarft antennas for satellite communications", Microwave Journal Oct. 1977, p. 38. The reason is that circular polarization can be regarded as a combination of a vertical and a horizontall polarization with 90.degree. phase shift. If the antenna is mounted on the surface of the vehicle, the horizontal polarization component of the field, which is thus parallel to the surface of the vehicle, will be short-circuited while the vertical polarization component at right angles to the surface is only decreased or attenuated by a certain amount (approximately 3.2 dB). Hereinafter, a horizontal and a vertical polarization component are respectively defined as components parallel and perpendicular to an electrically conductive surface (the surface of the vehicle). The loss in a circular-polarized antenna outside the vehicle will be a further 6 dB, however, of which 3 dB is because only vertical polarization can be seen, and a further 3 dB in the feed network, since both polarization components are fed.